Many devices and systems produce waste thermal energy, which is typically lost to the environment and results in inefficiencies in operation of such systems. For example, electrical equipment produces waste heat, which can adversely affect operation of the equipment, thereby requiring various approaches to remove the heat from the system, and potentially requiring additional energy. Systems which have been used to remove waste heat in such situations include forced air systems, heat exchanger systems, heat radiating structures or others, which assist in removing waste heat from the vicinity of the heat source.
Other systems, such as mechanical devices, may also produce waste heat in their operation, due to friction, energy conversion or other operational characteristics. Again, in such systems, waste heat may simply vent to the environment or cooling systems are used to dissipate or remove waste heat from the system.
In still other systems, such as biological systems, waste heat may be generated due to physiological processes for example.
In each of these types of systems, as well as a variety of other possible systems and situations, unintended thermal energy may present problems in the desirable operation and function of such systems, or simply may be lost to the environment.
There have also been developed various systems for converting thermal energy to other energy forms, whether the thermal energy is generated intentionally or unintentionally. As examples, recovery of thermal energy may be possible using heat pumps, including chemical heat and cooling pumps, thermal-acoustical heat and cooling pumps, Stirling cycle systems, or various other systems for capturing and converting thermal energy for re-use. Similarly, various systems have been developed for conversion of thermal energy to other useful forms of energy, including pyro-electrical conversion, thermal-electrical conversion, thermal ionic conversion, gas cycle conversion systems, such as Stirling devices, Brayton, etc., and absorption cycle systems as examples. Devices for conversion of thermal energy to other energy forms have historically been large, and in many cases require moderate-to-high temperature differentials for effective operation. Further, such systems include mechanical components, which are subject to friction and wear, limiting the efficiency of the system. Further, contemporary conventional conversion processes and manufacturing processes limit the device size to dimensions much larger than are compatible with many of the types of systems where thermal energy is generated.
It would therefore be worthwhile to provide methods and systems which can convert thermal energy into electrical power and which overcome limitations associated with the foregoing systems and approaches. It would also be desirable to provide such capabilities in a meso-to-micro scale device, wherein micro-electro-mechanical systems (MEMS) technology, allows the manufacture of devices having sizes which are greatly reduced from prior art systems.